Drill



Patented Aug. 21, 1934 UNITED STATES DRILL Walter C. Rea, New York, N. Y., assignor to Detachable Bit Corporation of America, New

York, N. Y., a corpor ation of Delaware Application April 8, 1930, Serial No. 442,495

3 Claims.

This invention relates to drills of the type comprising a drill rod and a bit detachably carried therewith, and more particularly to means for coupling such rod and bit.

It has already been proposed to use a threaded coupling member to secure a bit to a drill rod in constructions of this character. When such a drill is percussively driven, as is usual, it is desirable that the impacts be transmitted di- ,rectly from rod to hit or bit to rod, to relieve the coupling and the threads of such forces. At the same time, the tendency of the coupling, due to rotation of the drill, to become wedged or jammed on either the rod or the bit is to be 5 avoided.

The principal object of this invention, is, therefore, to provide an improved construction whereby these desired advantages are secured and which is simple and inexpensive to manufacture, rugged and durable in service, and capable of being readily disassembled into its parts even after the drilling operation.

A further object of the invention is theprovision of means for preventing wedging of the coupling upon rod. or bit, said means being within the coupling.

Another object is the provision of a coupling which is inexpensive to manufacture and readily attachable and detachable.

Other and further objects and advantages of this invention will appear from the following de tailed description of a specific embodiment thereof, reference being had to the accompanying drawing, wherein:

Fig. l is a sideview ,of a portion of a drill rod in accordance with the present invention. Fig. 2 is a, section through the coupling member which secures the bit to the drill rod. Fig. 3 shows a bit in accordance with the present invention. Fig. 4 is a sectional elevation showing the parts assembled as they are in operation of the drill.

There is shown at 1 a portion of a hexagonal drill rod or shank having a circular portion as indicated at 2, and undulating coarse threads 3 '45 of continuously curved contour more fully described in Reissue Patent No. 17,557 granted January 7, 1930 to Fred W. Thurston. The end of the shank is formed with-a shoulder 4 which is circumferential.

At 5 there is illustrated a coupling member which is hollow as at 6 and internally threaded as at '7. The threads '7 are adapted to cooperate with the threads 3 on the shank so that when the drill is rotated the tendency is for the coupling member to turn more tightly on the shank,

These threads end adjacent a flange 9 formed on the interior of the coupling member. This flange is preferably circumferential and formed with square corners, or in other words with sides 10 which are perpendicular to the axis of the drill rod. Similarly, the shoulders 4 are formed with square corners. The other end of the coupling member is similarly threaded as at 11 to coopererate with the threads 13 on the bit 12, so that the bit will also tend to be tightened into the coupling in operation of the drill, the threads on the rod and bit running in the same direction. The' bit 12 is also formed at its end with a circumferential shoulder 14, similar to the one on the drill rod.

It will be noticed that the width of face 15 of flange 9 is greater than the height of either face 16 or 17 of the shoulders on the flange and bit. The purpose of this is to prevent the flange from becoming wedged against the oppositeshoulder when the coupling member is at one end of its travel. The width of the flange is less than the combined heights of the shoulders so that some travel of the coupling member is permitted and so that the ends 8 and 8' of the shouldered portions of the bit and shank abut directly against one another. The threads on the flange and bit, respectively, extend a greater distance from their ends than the distances from the respective ends of the coupling member to the adjacent sides of the flange. This is, of course, necessary in order that the flange and shoulders may cooperate to prevent excessive travel of the coupling member, thereby avoiding any wedging or splitting of said member. In the form of the invention illustrated the end portions of the drill rod and bit which abut to form the joint 88 are of minimum cross sectional area of material and are less than the cross sectional area of the adjacent threaded portion. This is in order to provide the clearance to accommodate the flange 9. The presence of the flange, however, provides for maximum strength of material in the coupling adjacent its midportion and this portion of the coupling with its maximum cross section of material at the joint 8-8 compensates for any weakening effect which might otherwise be present in the drill rod as a whole at the joint. In devices of this character there is a tendency of the coupling to break at the joint between the drill rod and bit but the flange at this point of possible breakage tends to reinforce the coupling and at the same time provide extra material at this point without increasing the diameter of the coupling which, of course, must be within the axially projected outlines of the bit in order to pass freely into the hole formed by the bit. It is not absolutely necessary that the comers on the flange and shoulders be square, but it is found that when the coupling member so formed comes to the end of its travel, that is when the flange abuts against the shoulder, there is less likely to be any sticking or wedging between the parts. The threads shown are of the undulating type, but it is not necessary that this preferred form be used. The present invention not residing therein.

A passage 18 extends lengthwise through the rod and bit for the passage of fluid, as is customary in the art.

It will be seen that in the present invention the coupling member is reversible or in other words may be attached at either end to the bit.

It will be appreciated that the specific embodiment of my invention described herein is subject to many modifications within the skill of a mechanic. This invention is not to be limited to the specific form illustrated but only by the scope of the appended claims.

What I claim is:

1. A sectional impact mining drill having a coupling, said sections and coupling being formed with and united by screw threads running in the same direction to maintain the sections in abutting relation with each other when the drill is rotated, and said coupling having within it a stop engageable with one of said sections to prevent the coupling from moving to the terminal parts of the threads of said threaded sections.

2. A rotary impact mining drill composed of separable sections and a coupling, said sections and coupling being formed with and separably united by screw threads of smooth, curved and undulatory form, the threads of said sections and coupling running in the same direction to maintain the sections in abutting relation when the drill is rotated, and said coupling having within it a stop engageable with either of said sections to prevent the coupling from moving to the inner termination of the threads of said threaded sections.

3. A rotary impact mining drill composed of separable sections and a coupling, said sections and coupling being formed with and separably united by screw threads running in the same direction to maintain the sections in abutting relation when ,the drill is rotated, a peripheral shoulder adjacent the abutting end of each of said sections, together forming an external groove when the sections are in abutting relation, and an internal peripheral flange on said coupling adapted to be disposed in said groove when the parts are assembled, said coupling having a limited travel in an axial direction on said sections and said flange being engageable with either of said shoulders to prevent the coupling from moving to the inner termination of the threads of said threaded sections.

WALTER C. REA. 

